A bulk type superconducting material made by melt processing method will be explained as an example of known art. The bulk type superconducting material made by melt processing method including yttrium-based material (for example, Y—Ba—Cu—O superconducting bulk magnet) can generate a strong magnetic field which is extremely higher than conventional permanent magnet. Therefore, this superconducting bulk magnet has been studied for applying it to a sputter gun of a magnetron sputtering coating apparatus. For example, JPH10-72667A discloses a magnetron sputter coating apparatus with a superconducting bulk magnet as a sputter gun. In addition, JP2002-146529A discloses a magnetron sputter coating apparatus with plural superconducting bulk magnet as a sputter gun.
Furthermore, as a part of development of the superconducting magnetic field generating apparatus, the applicant of the present invention has been developed (hereinafter referred to as development example) wherein a yoke forming a magnetic circuit is fixed to a vacuum chamber side, as shown in FIGS. 11–13. According to this configuration, since the yoke is fixed to the vacuum chamber side, a magnetic field distribution generated from the superconducting body can be corrected using the yoke.
FIG. 11 shows an illustration of the superconducting magnetic field generating apparatus 1X according to the development example. FIG. 12 shows an illustration of a condition before attaching the superconducting magnetic field generating apparatus 1X to the sputter coating apparatus 200X according to the development example. FIG. 13 is an illustration of a condition after attaching the superconducting magnetic field generating apparatus 1X to the sputter coating apparatus 200X according to the development example.
Hereinafter configuration of the development example will be explained with reference to FIG. 11. A superconducting body 2X and a lower yoke 63X are accommodated in a thermal insulation vessel 3X which is kept to high vacuum condition. The superconducting body 2X, the lower yoke 63X and the thermal insulation vessel 3X are fixed to a cold head 41X of a cooling member 43X.
Excitation method of the superconducting body 2X will be explained below. The thermal isolating vessel 3X accommodating the superconducting body 2X is inserted to an opening of a superconducting magnet 100X. With applying a designated magnetic field to the superconducting magnet 100X, the superconducting body 2X is cooled to below critical temperature of superconduction. In this condition, the superconducting body 2X acquires the magnetic field. After the designated magnetic field is turned off, the thermal insulation vessel 3X accommodating the superconducting body 2X is removed from the opening of the superconducting magnet 100X.
For the superconducting magnetic body 2X, although the lower yoke 63 is provided under the superconducting body 2X, a ring yoke 61X is not provided along the outer circumference of the superconducting body 2X. Therefore, line of magnetic force 67m is spread above the superconducting body 2X (upward direction in FIG. 11) with wide area.
As shown in FIG. 12 and FIG. 13, a ring yoke 61X made of ferromagnetic body is fixed to a vacuum chamber 204X side of the sputter coating apparatus 200X. For attaching the superconducting magnetic field generating apparatus 1X to the sputter coating apparatus 200X, the superconducting magnetic field generating apparatus 1X and a cooling member 43X are placed under attaching portion of the sputter coating apparatus 200X as shown in FIG. 12. Next, the superconducting magnetic field generating apparatus 1X is jacked up using a lifting member 48X (jack), and inserted to opening of the ring yoke 61X as shown in FIG. 13. Then, the ring yoke 61X is placed along the outer circumference of the superconducting body 2X.
When the superconducting magnetic field generating apparatus 1X is attached to the sputter coating apparatus 200X, misalignment caused by attractive force between the superconducting body 2X and the ring yoke 61X since the ring yoke 61X is fixed to the vacuum chamber 204X. Therefore, a damper 210X and a guide 211X are provided as an attaching means to prevent misalignment.
Also, to prevent crashing of inner wall of the superconducting body 2X and the ring yoke 61X, a strong construction is needed for attaching means (the damper 210X and the guide 211X), and the apparatus becomes large and complicated structure.
In addition, as shown in FIG. 11, the thermal insulation vessel accommodating the superconducting body 2X is exposed until the super conducting magnetic field generating apparatus 1X is attached to the sputter coating apparatus 200X.
In addition, when a target 206X of the sputter coating apparatus 200X is replaced, to release the target 206X from magnetic force, the super conducting magnetic field generating apparatus 1X is moved to downward. In this operation, magnetic field distribution by the superconducting body 2X is changed with separating the superconducting body 2X from the ring yoke 61X. Therefore, changing frequency of both magnetic force and magnetic field distribution of the superconducting body 2X is increased with increasing frequency of replace, and magnetic force and magnetic field distribution is attenuated.